What is Saju, and how do you read a Korean birth chart?

Saju (사주) is the Korean birth chart. It takes the moment you were born — year, month, day and hour — and writes each one as a pair of classical characters. Four pairs, eight characters: that is the whole chart, and everything a reading says comes from how those eight characters relate to each other. This guide walks through one chart from start to finish so the words on your own result make sense.

Four pillars, eight characters

The full name is saju palja (사주팔자), “four pillars, eight characters”. Each pillar is a column with a heavenly stem on top and an earthly branch underneath. There are ten stems and twelve branches, and they pair up in a fixed sixty-step cycle — the same cycle that names years like 갑진 (2024) or 을사 (2025). Every stem and every branch belongs to one of the five elements — wood, fire, earth, metal or water — and is either yin or yang. So the chart is really eight small labels: eight elements, eight polarities, arranged in four columns.

Where each pillar comes from matters, because it is where most calculators go wrong:

• Year — the Korean solar year, which begins at ipchun (입춘, around 4 February), not on 1 January. Someone born in late January belongs to the previous year's pillar.
• Month — set by the twelve solar terms (절기), not by the calendar month. Each “month” starts at a specific term such as 청명 in early April.
• Day — a continuous sixty-day cycle that has run unbroken for centuries; there is nothing to look up except the count.
• Hour — twelve two-hour blocks, each with its own branch. 09:30 falls in the 사 (巳) hour, 09:00–11:00, adjusted for the time zone of the birthplace.

One chart, read in order

Take a fictional person born on 12 April 1995 at 09:30 in Seoul — the same chart used in our sample report. The calculator gives:

Step 1 — find the Day Master

The heavenly stem of the day pillar is the Day Master (일간). It is the character that stands for the person; everything else in the chart is read in relation to it. Here the day pillar is 癸酉 (계유), so the Day Master is 癸 — yin water. In Korean readings the whole day pillar is also treated as a type of its own: 계유일주, which our calculator describes as “The Morning Rain” — rain and morning dew, soft and reaching everywhere. That label is a traditional character sketch, not a personality test.

Step 2 — count the elements

Now count how many of the eight characters belong to each element:

Water and metal appear twice each, fire twice, wood and earth once. No element is missing. When an element does come out at zero — which is common — it is a note about where the chart leans, not a flaw; Korean tradition responds to it with balance, and naming is one of the places that balance is applied.

Step 3 — ask how the Day Master is supported

A count is where a reading starts, not where it ends. The next question is whether the Day Master is well supported. Two things support yin water: other water, and metal, because metal generates water in the cycle of the elements. Working against it: wood, which water feeds, and earth and fire, which it has to push against. This chart was born in an earth month (辰), which does not help water, but its day branch 酉 is metal, which does. Weighing everything, our calculator reads this Day Master as weak — supported by well under half of the chart.

That verdict is what decides the last line of a reading: what the chart calls for. A weak water Day Master calls for water first and metal second — in the traditional terms, 용신 water and 희신 metal. The free calculator ends there. The name side of our work begins there: hanja whose element is water or metal are the ones that answer this chart.

How the weighted reading differs from the simple count is the subject of the next guide: Saju five elements: how to read your chart's balance.

If you don't know your birth time

Leave the hour out. The year, month and day pillars are still exact, so the Day Master, the six-character count and the support question all still work. What you lose is the hour pillar itself, and readings that lean on it — traditionally, the parts about later life and children. Our calculator marks the hour as unknown instead of assuming noon or midnight; a reading that quietly fills in a time is reading a different person.

Terms you will meet

Saju 사주 四柱

Literally “four pillars”: the Korean birth chart built from the year, month, day and hour of birth.

Saju palja 사주팔자 四柱八字

The full name of the chart: four pillars, eight characters. Each pillar contributes one heavenly stem and one earthly branch.

Pillar 주 柱

One column of the chart. The year, month, day and hour pillars are each a stem-and-branch pair.

Heavenly stem 천간 天干

One of ten characters (甲乙丙丁戊己庚辛壬癸) that sit on top of a pillar. Each carries an element and yin or yang.

Earthly branch 지지 地支

One of twelve characters (子丑寅卯辰巳午未申酉戌亥) that sit under a pillar. Each carries an element and yin or yang, and each is also one of the twelve animal signs.

Day Master 일간 日干

The heavenly stem of the day pillar. It stands for the person, and every other character is read in relation to it.

Day pillar 일주 日柱

The day’s stem-and-branch pair. Sixty combinations exist; each is treated as a recognisable type in Korean readings.

Five elements 오행 五行

Wood, fire, earth, metal and water. Every stem and branch belongs to one of them, and the chart is read as a balance between the five.

Yin and yang 음양 陰陽

Each stem and branch is either yin or yang. The Day Master’s polarity is part of its character.

Hidden stems 지장간 支藏干

Stems considered to be contained inside each earthly branch. They are why a weighted reading of the chart differs from a simple count of characters.

Yongsin and huisin 용신·희신 用神·喜神

The element the chart calls for first, and the one that supports it. In Korean naming these set the elemental direction for choosing hanja.

Hour pillar unknown 시주 미상

When the birth time is not known, the chart is calculated from three pillars (six characters) and the hour pillar is left blank rather than guessed.

How this guide was made

The chart above was calculated by the same engine that runs our free calculator, from a fixed fictional birth, and the tests that build this site check it against the sample report so the two can never disagree. The rules — solar-term boundaries, day cycle, hidden stems, how support is weighed — are written out on our methodology page. Nothing here predicts events; Saju is presented as a cultural tradition and a way of reflecting, and that is how we use it when we choose names.

Ready to see your own eight characters? Calculate your free Saju chart — nothing is stored, and the hour is optional. If you want the written reading of your chart, see what the full Saju reading contains.